Pimsleur's Mandarin course teaches 'both of us' as 我们两个都 (wǒ men liăng ge dōu)
, but in another question I asked here I recently found that 我们俩 (wǒ men liă)
.
Are these always interchangeable, or are there any rules concerning when to use one over the other? Are there any more ways to say 'both of us'?